Configurable Buoyancy And Geometry (CBAG) Airship

ABSTRACT

A lighter-than-air semi-rigid airship has Configurable Buoyancy And Geometry (CBAG) allowing it to become short and plump for maximum buoyancy during takeoff and landing, but also allowing it to become long and slim for reduced drag (albeit less buoyancy) so that it may travel at high speed. It may be combined with a heavier-than-air structure having wings or rotors to form a hybrid aircraft whereby the wings or rotors provide enough lift to compensate for the reduced buoyancy during high-speed flight.

CROSS REFERENCE TO RELATED PATENTS

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STATEMENT OF FEDERALLY SPONSORED RESEARCH

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PARTIES TO A JOINT RESEARCH AGREEMENT

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REFERENCE TO A SEQUENCE LISTING, TABLE, OR COMPUTER PROGRAM

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BACKGROUND OF THE INVENTION

Lighter-than-air airships use a lifting gas—most commonly helium,hydrogen, or hot air—to provide buoyancy, and may be classed asnon-rigid, semi-rigid, or rigid. Non-rigid airships such as early blimpsand hot air balloons have an envelope that is supported only by thepressure of the gas within. Semi-rigid airships typically have someinternal structure but still rely on internal pressure to inflate theenvelope. Rigid airships such as dirigibles have a mechanical structurethat supports and maintains the shape of the outer envelope while thelifting gas is typically contained in multiple smaller internal gaschambers.

Lighter-than-air airships are useful because they can take off and landvertically and can stay aloft for long periods using little or no fuelunless they use hot air as the lifting gas. However, they do have someserious disadvantages. They are limited to low speeds because they havea very large frontal area with a rather delicate outer skin. The newestblimps have a maximum speed of about 70 MPH. Lighter-than-air airshipstend to be very expensive if they use helium, and very dangerous if theyuse hydrogen, which is much cheaper but highly flammable. Anotherproblem is that in order to land, an airship must be slightly heavierthan air, or use its engines to produce some downward force. Once on theground, it typically needs to be tethered to keep it down or broughtinto a hangar to protect it from the wind. At high altitude, where theatmospheric pressure is reduced, the internal gas may develop too muchdifferential pressure if it is not vented or pumped into a pressuretank. Some airships are designed to be slightly heavier than air andmust use their engines to take off and stay airborne.

In 1670, an airship was proposed using vacuum filled spheres forbuoyancy, which initially sounds like a great idea, because a vacuum islighter than any lifting gas. However, scientists have argued that anyspherical structure strong enough to support a vacuum against the crushof atmospheric pressure would be too heavy to be lifted by the enclosedvacuum. However, this does suggest that if an airship could be designedsuch that its lifting gas would be at a partial vacuum, it would havegreater buoyancy.

BRIEF SUMMARY OF THE INVENTION

The present invention overcomes many, and perhaps all, of theshortcomings of previous lighter-than-air airships. Because it providesa Configurable Buoyancy and Geometry, it can [[be]] become significantlylighter or heavier than the air it displaces, enabling vertical takeoffand landing (VTOL) without the need for thrust or ballast. It can alsoreduce its frontal area and drag to be more streamlined, while at thesame time becoming more rugged and durable, allowing it to travel athigh speed. It is anticipated that such a craft will be able to travelat well over 100 MPH, possibly even 200 MPH. Yet, it has a very simple,inherently strong, lightweight, and low-cost semi-rigid structure andoperating mechanism. It requires no ballast, no multiple separate gaschambers, no pumps, pressure tanks, or blowers, and no complex controlschemes. In addition, the internal gas can be at a partial vacuum,further increasing its buoyancy over that of a similar volume airship inwhich the gas must be above atmospheric pressure to inflate and supportthe envelope. This also reduces the problem of excessive internalpressure at high altitude. A further advantage is that if there were anyleakage or permeability in the envelope, rather than expensive helium ordangerous hydrogen leaking out, relatively harmless air would leak in,which could be continuously liquefied and eliminated by a miniaturecryogenic system. The reduced internal pressure would help to make ahydrogen-filled airship safe and practical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the CBAG airship configured for maximumbuoyancy.

FIG. 2 is a side view of the CBAG airship configured for minimumbuoyancy.

FIG. 3 is a section across the middle of the CBAG airship configured formaximum buoyancy.

FIG. 4 is a section across the middle of the CBAG airship configured forminimum buoyancy.

FIG. 5 is a section across the middle of a possible rib structure.

FIG. 6 is a side view showing an internal tensioning mechanism adjustedfor maximum buoyancy of the CBAG airship.

FIG. 7 is a side view showing an internal tensioning mechanism adjustedfor minimum buoyancy of the CBAG airship.

FIG. 8 is a front view showing the CBAG airship at maximum buoyancycombined with a heavier-than-air fixed wing aircraft.

FIG. 9 is a front view showing the CBAG airship at minimum buoyancycombined with a heavier-than-air fixed wing aircraft.

FIG. 10 is a bottom view showing the CBAG airship at maximum buoyancycombined with a heavier-than-air quad-copter drone.

FIG. 11 is a bottom view showing the CBAG airship at minimum buoyancycombined with a heavier-than-air quad-copter drone.

DETAILED DESCRIPTION

FIG. 1 shows the CBAG airship 100A adjusted for maximum buoyancy. Asuitable internal or external mechanism (not shown) as shown in FIG. 6forces the nose and tail slightly closer together shortening the overalllength, forcing the ribs 101 to bow outward, greatly increasing thevolume and displacement of the airship, while at the same time reducingthe internal gas pressure. This action stretches the envelope 102 tightbetween against the ribs. For simplicity, the drawings show the overallshape as a symmetrical ellipsoid, but in practice, the shape could beengineered to be more streamlined for improved aerodynamics, or to beotherwise asymmetrical to optimize its utility.

FIG. 2 shows the CBAG airship 100B adjusted for minimum buoyancy. Thesame mechanism gradually allows the nose and tail to move farther apart.This action allows the ribs to become less bowed and move inward towardthe centerline, partly due to the built-in springiness of the ribs, andpartly due to atmospheric pressure pushing on the outside of theenvelope against the lower gas pressure inside.

FIG. 3 shows across section through the middle of the CBAG Airship 100Aat maximum diameter and buoyancy, showing the individual ribs 101separated by wide segments of envelope 102.

FIG. 4 shows the same cross section through the middle of the CBAGAirship 100B configured for minimum diameter and buoyancy, such that theribs move closer together till they meet, forming a closed hard shell.Atmospheric pressure causes the thin flexible envelope material toneatly fold inward between the ribs as they gradually move closertogether.

FIG. 5 shows a simplified cross section detail of one possible ribstructure and its relationship to the envelope sections. Two ribsections are shown. Each rib 101 includes a wide outer shell 103 and twonarrow inner shells 104. The edges of the envelope sections 102 aresandwiched between the inner and outer shells. (The size and spacing isexaggerated for clarity.) The inner and outer shells, and the envelopematerial could be joined together by adhesive, removable fasteners, orany other appropriate means. This method of assembly might make itunnecessary to have sewn seams in the envelope, reducing cost andweight. The inner shells are made narrower than the outer shells so asnot to damage the envelope by pinching it when the outer shells meet.The outer shells could be made with tongue and groove joints or the liketo make the structure more ridged. The inner or outer shells could alsoinclude longitudinal ridges or other structures for added strength. Theribs could possibly be made of aluminum, but modern composite materialsmight provide higher strength at less weight, and possibly lower cost.

In the construction of a modern blimp, the entire envelope must beformed into one or two very large pieces before it is applied to theinternal structure, which is a very complex and costly process. In thepresent invention, the rib structure makes it possible to install theenvelope one segment at a time in a much simpler and less costlyprocess.

While not shown in the drawing, As shown in the drawings, there wouldpreferably be a rugged nose assembly at the front end and a similar tailassembly at the back end to anchor the ribs and keep them properlyaligned. The nose and tail assemblies would also serve as anchor pointsfor the mechanism that adjusted the length of the CBAG airship toconfigure its buoyancy and geometry. The simplest and lightest mechanismwould probably be a simple electric powered cable winch mounted inside,but a motorized jackscrew, or a pneumatic or hydraulic cylinder couldalso be used. Because it only takes a small change in length to producea large change in diameter and buoyancy, the jackscrew or cylinder wouldnot need to be very long. For example, if the airship were 100 feet longand 10 feet in diameter at minimum buoyancy, it would only have to beshortened by 2½ feet to double its diameter. The adjustment mechanismcould be mounted in the nose or tail assembly for easy servicing.

Some of the ribs could be fitted with appropriate means to allowattachment of various external features such as fins, engines, or asuspended gondola, as long as the attached features did not interferewith the normal flexing of the ribs as they change shape. The nose andtail assemblies might provide a more stable structure for attaching suchfeatures.

While the CBAG could certainly be fitted with its own attached wings,fins, propulsion, control, and navigation systems, etc., its greatestadvantages would most likely be realized when combined with a customdesigned heavier-than-air aircraft structure using wings or rotors thatwould provide all those features, along with space for crew, passengers,cargo and fuel or batteries. This structure could be slung under theCBAG, suspended either from the ribs, or from the nose and tailassemblies. If attached to the nose and tail assemblies with rigidmembers having the ability to pivot or telescope, this structure couldapply an external force to configure the buoyancy and geometry. Thewhole under-slung structure could be moved slightly forward or backwardto trim the pitch angle of the combined hybrid craft. For a largetransport system, two or more CBAG Airships could be combined with aheavier-than-air structure. For an electric powered craft, wings couldbe fitted with solar panels.

In the case of a quad-copter style aircraft, adding one or more CBAGAirships would make it possible for such a craft to stay aloft muchlonger, as power would only be needed for changing position or stationkeeping, instead of for hovering. An electric powered craft with solarrecharging could stay aloft almost indefinitely. Such a device couldfunction as a cellphone or microwave relay station, or as a long-termreconnaissance drone.

In an alternate embodiment, though perhaps more complicated and lessoptimal, the ribs could be designed to inherently bow outward formaximum buoyancy with the lifting gas at close to atmospheric pressure,and they could be drawn inward along with the envelope by pumping gasout of the envelope and into a pressure storage tank, or by an internalmechanism acting directly on the ribs to draw them in.

In a lighter-than-air semi-rigid airship of the type having an outergas-tight envelope of an approximately ellipsoidal shape containing alighter-than-air gas, supported by a plurality of springy flexiblelongitudinal ribs, bowed outwardly from a center axis by a tensioningdevice pulling opposite ends towards each other, I claim:
 1. (canceled)2. (canceled)
 3. (canceled)
 4. (canceled)
 5. (canceled)
 6. (canceled) 7.(canceled)
 8. A Configurable Buoyancy And Geometry (hereinafterabbreviated CBAG) Airship comprising: a nose assembly and a tailassembly, said assemblies positioned at opposite ends of a geometriccenter axis; an array of springy longitudinal ribs arranged in a radialpattern about, and bowed outwardly from said center axis; said ribshaving front ends fastened to said nose assembly and having back endsfastened to said tail assembly; a thin flexible lightweight gas-tightenvelope formed by individual segments, each segment located between twoadjacent ribs and attached thereto, said envelope forming an enclosedvolume of space defined by said nose assembly, tail assembly, and ribs;said envelope containing a lighter-than-air gas, said gas being at aslight negative pressure relative to ambient atmosphere to increase itsbuoyancy and to keep the envelope tight against the ribs, with means toconfigure said buoyancy by adjusting the size of the enclosed volume ofsaid envelope
 9. A CBAG Airship as in claim 1 which includes aremote-controlled tensioning device connected between said nose assemblyand tail assembly disposed to configure the geometry and buoyancy ofsaid airship by a.) pulling the nose and tail assemblies closertogether, thus forcing the ribs to bow further outward to graduallyincrease the enclosed volume and buoyancy to a maximum value, and by b.)allowing the nose and tail assemblies to move further apart, thusallowing the ribs to move closer to the center axis to gradually reducethe enclosed volume and buoyancy to a minimum;
 10. A CBAG Airship as inclaim 1 whereby each longitudinal rib has a hard outer shell, each shellhaving a first and second longitudinal edge with a tongue along a firstedge and a groove along a second edge such that when the volume andbuoyancy are at a minimum the tongue of each shell will fit into thegroove of an adjacent shell completely enclosing the envelope of theairship to enable high speed flight with minimum aerodynamic drag
 11. ACBAG Airship as in claim 1 which can be combined with a heavier-than-airwinged aircraft to form a highly optimized hybrid aircraft whereby thebuoyancy of the CBAG Airship can provide the buoyancy for verticaltake-off and landing, and as said winged aircraft accelerates to providelift from its wings, the CBAG airship can be configured in-flight forminimum buoyancy to reduce drag allowing high-speed flight
 12. A CBAGAirship as in claim 1 which can be combined with a heavier-than-airrotor craft drone to form an optimized hybrid aircraft whereas the CBAGAirship can provide the buoyancy for vertical takeoff, hovering, andlanding, but can be configured in-flight for minimum buoyancy to reducedrag allowing high speed flight